Filipin II is a minor component of the filipin complex, a family of pentaene antifungal metabolites first isolated from Streptomyces filipinensis and reported by researchers at Upjohn in 1955. Structurally, filipin II lacks the hydroxy moiety on the pentyl side chain and is more hydrophobic, eluting later than filipin III on reverse phase HPLC. Filipin II is a potent broad spectrum antifungal agent that also exhibits antitumor and antiviral activities and acts by binding cell membrane sterols, disrupting membrane integrity.